Meaning

originFrom Middle English ah, aa, a (“ah”), of imitative origin, or from Old English ēa, *eah (“oh, alas”), from Proto-West Germanic *a, *ah (“ah”). Earliest recorded use is circa 1175 in the Ormulum: A, Maȝȝstre! icc wat tatt tu full wiss Arrt Godess Sune ("Ah, Master! I know for sure that thou art God's Son"). Some propose that the Middle English is borrowed from Old French a (“ah!, oh!, hey!”)…

Etymology from Wiktionary, CC BY-SA 3.0